Carton with snap lock bottom closure



Dec. 21, 1943. GARDNER; JR 2,337,039

CARTON WITH" SNAP LOCK BOTTOM CLOSURE Filed May 14, 1941 INVENTOR.EDWARD T Gnkalvslgvja BY mew-M- ATTORNEYS- Patented Dec. 21, 1943 CARTONWITH SNAP LOCK BOTTOM CLOSURE Edward T.

Gardner, Jr., Dayton, The Gardner-Richardson Company,

Ohio, assign'or to Middletown, Ohio, a corporation of Ohio ApplicationMay 14, 1941, Serial No. 393,457

1 Claim.

My invention relates to cartons having for a bottom closure a series ofclosure flaps, one articulated to each main wall of the carton, whichclosure flaps are so configured that they may be interengaged andinterlocked by a simple inthrusting motion after the fiaps have beenfolded over in the correct order. Such cartons are useful for a varietyof purposes and products, and are of commercial interest in instanceswhere a relatively large number of cartons must be set up and closed onthe bottom, by hand rather than by machine, and where the gluing of thebottom closure of a carton is impracticable or undesired. A number ofsnap-lock cartons have been suggested in the past; but all of these haveeither been characterized by such an interengagement of the closureflaps as would permit racking or diagonal distortion of the bottom, orby such an interengagement of the flaps as would permit accidental andundesired opening of the carton by pressure of weight from within, or byboth of these defects. Again, certain structures have been suggestedwhich, while permitting interengagement of the bottom flaps, areincapable of acting automatic 11y, i. e. of interlocking of themselvesupon being displaced inwardly, but require extra manipulations ofvarious kinds. In the art a snap-lock carton has such a structure thatif the closure panels are folded over in a predetermined order, and thefolded structure pressed inwardly, it will upon release form an engagedbottom closure. It may be necessary in some instances to press theengaged panels outwardly, or to cause the inserted contents to do this;but in a snap-lock carton as understood in the art no othermanipulations, such as the folding over or insertion of tabs or lockingmeans, or the bending of flaps, are necessary. This is what I meanhereinafter by the references to the automatic actionof my cartons.

The primary object of my invention is the provision of a cartonstructure such that the interengagement of the flaps to form the lockedbottom is not only easily and automatically effected, but when onceefiected provides a structure which is very much more resistant toopening than automatically acting structures heretofore produced, whileat the same time it is not subject to racking. Since my carton does nothave these defects, large boxes carrying heavy weights and weightsunevenly distributed may be made in accordance with my invention. WhileI have spoken of cartons, it will be understood that my invention is notlimited to containers of any particular size or containers made of anyparticular weight of board. Thus, the principles of my invention may beapplied to cartons in the ordinary acceptance of that term where thecartons are made of any of the usual weights of box board or to shippingcontainers made of very much heavier boards and usually of pastedboards.

The primary object of my invention as set forth, and other objects whichwill be indicated hereinafter or will be apparent to one skilled in theart upon reading the specification, I accomplish by that certainconstruction and arrangement of parts of which I shall now describe anexemplary embodiment. Reference may be made to the drawing wherein:

Figure 1 is a plan view of a blank showing the bottom closure membersand at least portions of the side walls of the carton.

Figure 2 shows the blank in knocked-down, glued conditions.

Figure 3 is a perspective view with portions cut away showing the insideinterengagement of flaps forming the bottom closure.

Figure 4 is a perspective view of the squared carton preparatory toclosing.

Figure 5 is a bottom perspective view of the carton showing theinterengagement of the flaps as apparent from the outside.

A snap-lock construction, such as that to which my invention isaddressed, is primarily useful in efiecting the closure of but one endof the carton, as will be readily understood. It could be used on bothends of the carton but only in the event the carton was set up andclosed while in unfilled condition or in the event that the carton wasfilled with some highly compressible substance.

This is because the snap-lock action requires a considerable inwarddepression of the several interengaged flaps. If the carton-. werefilled and closed on one end, such an inward depression would usually beprevented by the contents\of the carton. Consequently, such closures areem ployed for the most part only on one end of the,

carton, which end is the end closed first and is. therefore, usually thebottom. The nature of the closure on the other end of the carton is nota limitation upon my invention and I have, therefore, illustrated noclosure for the other end.

In Figure 1, I have shown a carton blank cut and scored to have mainwall portions A, B, C and -D which may be of any length appropriate tothe uses to which the carton is to be put. There is likewise in myinvention no limitation'as to the relative width of the sidewalls of thecarton. The side walls may be of equal Widths giving a square cartonwhen erected, or of quite unequal widths giving an erected rectangularcarton.

Since the closure is efiected by the interengagement of bottom flaps,the weight of the board as having articulated to it a glue flap E.Bottom flaps are indicated respectively at F, G, H and I.

The carton will be folded into a fiat, tubular knock-down formation withthe flap E adhered by glue or stitching to the wall A as is usual incarton manufacture. This condition is illustrated in Figure 2. Beforeuse, the carton will be squared up as shown in Figure 4. 'I'hereupon,the bottom closure flaps will be unfolded.

It will be noted in the several figures that the flaps G and I aretriangularin general configuration. In the diagonal edges of these flapsthere are notches l and 2 for a purpose hereinafter to be discussed. Theflap H has inwardly inclined side edges 3 and 4, terminating at points 5and 6, beyond which the edges are formed areuately outwardly as at 1 and8, and the fiap is extended outwardly to form a tongue 9 substantiallywider than the narrowest width elsewhere of the flap H. The fiap F is arectangular flap; but is characterized by a cut-out l intermediate itsedges and having a length substantially equal to the distance betweenpoints and 6 of flap H. The configuration of flaps F and H is such thatpoints 5 and 6 will lie along the base of the cut-out l0, andsubstantially midway of the carton bottom. It will be noted also thatthe edge of notches I and 2 which lies toward the outer end of flaps Gand I is curved.

In closing the carton, the flap F is first folded inwardly. Triangularflaps G and I are then folded inwardly over fiap' F, and finally flap His folded inwardly over flaps G and I. The structure is then locked bypressing inwardly at the center of the bottom so as to depress the wallsuntil the outer edge of the extension or tongue 9 passes inwardly beyondthe'outer edge of flap F.

The inward pressure is then released and the flaps tend to springoutwardly into locked posi-' tion.

The substantially'straight edges of the cuteout Ill permit fiaps H and Fto come outwardly into the plane of the bottom of the carton, the points5 and! riding along the edges of the cut-out Ill. The bottom of thecarton remainsclosed because the tongue 9 of the outermost flap H is nowengaged beneath the body of the innermost flap F. This prevents thebottom from opening because of the resiliency of the walls; .but theinterengagement thus fardescribed does not prevent the bottom from'opening in response to outward pressure from within the carton. I

V The diagonal side edges'of flaps G and I areso disposed as to liesomewhat inwardly of the points 5 and 6 of flap H when the carton isclosed. It is thus necessary for the points '5 and 6 to engagesubstantially in the bases of the notches l and 2, as shown most clearlyin Figure 5. The diagonaledges of the flaps G and H are so placed thatwhen the several fiaps are forced inwardly, the portions 1 and 8 of flapH will pass them. The forwardcurving edges of the notches l and 2 permitthe points 5 and 6 of flap H to ride down-into the engagementaforementioned, without jamming and without distortion of flaps or flapparts. There may be, and in instances preferably will be a slightbinding either overcome by the weight assaoae of the contents or by aslight pressure from within. But when the engagement is effected as inFigure 5, the flaps are securely interlocked, the

Y carton bottom is prevented from opening out- 5 wardly, and racking ordiagonal distortion of the carton bottom is likewise prevented. Yet theinterlocking action occurs automatically. Containers for heavy dutyusing my locking device may be strengthened against high internalweights by increasing the depth of the shoulders II and I2 on panels Aand C. Such an increase of the depth may cause the points 5 and 6 on theflap H to bind sufliciently so that the flaps will not spring outwardlyof their own accord; but by means of a slight outward pressure frominside, applied by the fingers, or by the contents of the box, thepoints 5 and 6 on panel H will easily slide along shoulders II and I2,and thus lock the bottom.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

In a closure for tubular cartons having four walls, closure flapsarticulated to each of said four walls, one of said flaps beingsubstantially rectangular in shape, extending somewhat beyond the medianline of the bottom of the carton, and having a cutout centrally locatedin the edge opposite its line of articulation with a base lyingsubstantially along said median line and side edges substantially normalto said base, the juncture of said side edges and base forming corners,an adjacent fiap having its forward portion out along a diagonal line sothat said fiap has substantially a triangular configuration, saiddiagonal line adapted to lie inwardly of a corner of the cutout in saidfirst mentioned flap, said second mentioned flap having a notch in saiddiagonal edge with a corner substantially coinciding with a corner ofthe cutout in said first mentioned flap, the forward edge at least ofsaid notch being formed arcuately to permit interlocking engagementwithout binding as hereinafter set forth, a' third. flap adjacent saidsecond flap, and of a length to bring its end beyond said median line ofthe bottom of said carton, the sides of said third fiap having notcheswith rounded are folded over, and a fourth flap having a configurationsimilar to the configuration of said second fiap but of oppositehand,the said construction of said fiaps being such that when said first fiapis folded over, said second and fourth flaps folded over on it, and saidthird flap folded over on said second and fourth flaps, and said foldedstructure depressed inwardly of the carton, the outer edge portion ofsaid third flap will pass the outer edge portion of said first fiap andthe diagonal edge'portions of said second and fourth flaps, and uponrelief of the inward pressure the flaps will spring outwardly intointerlocked condition, with said several notches in engagement, with theouter end of said third flap engaged beneath said first, second andfourth flaps, and with the notches on said third flap engaged in thecorners of the cutout of said first flap, whereby a structure isproduced not suscep tible to racking.

EDWARD T- GARDNER, JR.

